Ducting associated with rail track and installing apparatus

ABSTRACT

Ducting associated with rail track comprising a bed ( 13 ) located along at least a portion of the length of the rail track, the bed lying proximate the rails ( 11 ), a resiliently deformable cover ( 27 ) receivable over the bed and comprising a plurality of elongated channel members located in an end to end relationship having their flanges ( 29 ) extending downwardly and outwardly, the cover being intended to cooperate with the bed to define a duct able to accommodate conductors, optical fibres, cable and services. The bed has retention means ( 21 ) in the form a groove to receive and retain the lips ( 31 ) of the channel members. An apparatus having a carriage ( 73 ) is movable along the rail track to cause inward resilient deformation of the cover by pairs of rollers ( 71 ) to enable installation and withdrawal of the lips ( 31 ) from the grooves ( 21 ).

FIELD OF THE INVENTION

This invention relates to service ducting associated with rail trackwhich can be utilised to accommodate services such as telecommunicationscable, optic fibre, power cables, conduits and the like.

Throughout the specification the term “conductors and the like” shall betaken as including electrical wires, cables and the like which are usedfor the transmission of signals and electricity, optic fibrecommunications cable, fluid conduits and like services.

Throughout the specification the term “sleepers” shall be taken asincluding sleepers, railway ties or any like any form of support whichis used to support a rail track and which are located at spacedintervals along the track in providing that support

BACKGROUND ART

With the growth of communities and the increase in demand on utilitiesresulting from such growth together with the demand created by advancesin technology, there is an increased requirement to provide additionalconductors and the like for purposes of meeting the demand fortelecommunication, provision of power and other services in areas whichare already built up. As a result, significant infrastructure must beput in place in order to accommodate for the increased demand and inaccommodating for the increased demand there can be a significantdisruption to existing infrastructure and communities to accommodateexisting installations for the additional infrastructure. In built-upareas, this can be particularly difficult as it involves significantdisruption. In situations where the appropriate duct-work alreadyexists, the introduction of additional cables also can be particularlydisruptive. Even in cases where the existing duct-work enables theintroduction of additional cables by “threading’ them through theduct-work the action of “threading” any additional cables into theexisting duct-work is time-consuming and labour-intensive. In addition,expanding the additional services to remote locations and to accommodatefor the geographic expansion of communities involves considerable costin laying the cable over fresh ground.

In most communities, a form of railway system exists, whether it be aheavy-duty railway for the transportation of heavy commuter trafficand/or freight or alternatively light rail. Existence of such railwaysprovides the opportunity of associating the required communicationsducting with the rail track.

It has been conventional practice to provide ducting for conductors andthe like in association with rail track by locating such ductingunderground and adjacent to the rail track. This has involved a dual useof the railway land but otherwise presents few savings since theconstruction and servicing of the rail track forms a totally separatefunction from the construction and servicing of the ducting. In additionrailway authorities have been generally resistant to the dual use ofland associated with rail track due to the possibility of damage to thestructural integrity of the rail track foundation and disruption to theservices provided by the railway. In addition, there have been proposalsfor providing some duct-work in direct association with a rail track forthe purposes of accommodating conductors and telecommunications linkageswhich are associated with the running of the railway where suchduct-work forms a part of the railway structure. Examples of suchproposals which have been proposed for railway systems or other tracksystems are disclosed in AU-A-31645/95, U.S. Pat. No. 5,163,614, U.S.Pat. No. 5,823,114, FR2285491, DE401103, DE19712775, JP4304110 andJP6284542. None of the aforementioned proposals however provide systemswhereby additional conductors and the like can be readily introducedinto the associated duct-work to improve the carrying capacity.

A difficulty that exists in associating a service such as cablingduct-work with a rail track relates to the need to be able to servicesuch duct-work without causing undue disruption of a railway serviceassociated with the railway track. A further difficulty relates toproviding such duct-work with the rail track without the likelihood ofadversely affecting the structural integrity of the rail track. It isdesirable that if ducting for the purpose of accommodating conductorsand the like is associated with rail track such service does notsignificantly disrupt the operation of the railway associated with therailway track.

The preceding discussion of the background to the invention is intendedonly to facilitate an understanding of the present invention. It shouldbe appreciated that the discussion is not an acknowledgement oradmission that any of the material referred to was part of the commongeneral knowledge in Australia as at the priority date of theapplication.

DISCLOSURE OF THE INVENTION

Accordingly, the invention resides in ducting associated with a railroadrail track, said railroad track comprising a pair of parallel railssupported from a base, the base providing a bed proximate the rails andco-extensive with the rail track, a cover receivable over the bedcomprising a plurality of elongate channel members located in end to endrelationship having their flanges extending downwardly, said cover beingintended to cooperate with the bed to define a duct which is able toaccommodate the conductors and the like, retention means associated withthe bed and adapted to receive and retain the edges of the channelmembers, said edges being selectively disengageable and/or engagablewith the retention means by application of opposed and inwardly directedforces to the edges to cause resilient inward displacement of the edgesfrom the retention means.

According to a further preferred feature of the invention, adjacentlengths of said channel members are interconnected by sleeves whichextend between the abutting ends of adjacent channel members.

According to a preferred feature of the invention the edges are at leastpartially retained by the retention means by a resilient deformationinduced by engagement with the retention means.

According to a further preferred feature of the invention the ductingfurther comprises a support for conductors and the like which extendsalong the length of the bed. According to a preferred feature thesupport provides electrical and at least some vibrational insulation.According to a preferred feature of the invention the support issupported from the bed. According to a further preferred feature of theinvention, the support comprises a plurality of cradles located atspaced intervals along the bed, said cradles having a recessed uppersurface which is adapted to accommodate conductors and the like.According to a preferred feature of the invention, the rail trackincorporates sleepers which support the rails and which are located atregular spaced intervals along the length of track, said bed beingdefined in part by a transverse zone of the upper surface of thesleepers and wherein the transverse zone accommodates the support.According to a further preferred feature, the transverse zone of thesleepers is recessed.

According to a further preferred feature of the invention, the supportcomprises a tray extending along the bed and defined by a plurality ofinterconnected elongate, upwardly directed channel members supported inend-to-end relationship. According to a further preferred feature of theinvention, the flanges provided on the tray comprise the retentionmeans. According to one embodiment, the flanges are inclined to beconvergent towards each other, said flanges being adapted to receivebetween themselves the edges of the cover. According to a furtherpreferred feature of the invention, the base of each of the trayaccommodates the support which comprises an elongate support elementadapted to receive the conductors and the like. According to a preferredfeature of the invention, at least some of the conductors or the likeare embedded within the support. According to a further feature of theembodiment, the surface of the support element is of a recessedcross-sectional profile. According to a preferred feature of theinvention the recesses provided in the support are adapted to supportthe conductors in a one to one relationship. According to a preferredfeature of the invention the recesses are spaced vertically with respectto each other. According to an alternative feature of the embodiment,the support is associated with a closure which is intended to bereceived over the support to isolate the conductors or the like from theremainder of the duct. According to a further preferred feature of theinvention, the cover is adapted to cooperate with the support to enclosethe conductors and the like accommodated by the support.

According to preferred feature of the invention the support is supportedfrom the cover and is formed with at least one recess which is adaptedto support the conductor. According to one embodiment the support andcover are integral and the recess is formed on the inner face of thecover. According to a preferred feature of the invention the recess issubstantially closed and is provided with an entry which is normallyclosed and can be opened on deformation of the support.

According to a further preferred feature of the invention, the retentionmeans comprises a pair of retention members supported from the bed atspaced intervals there along, the retention members of each pair beingspaced to either side of the bed, the edges of the cover being receivedbetween the retention members. According to one embodiment, the railtrack incorporates sleepers which support the rails and which arelocated at regular spaced intervals along the length of track, said bedbeing defined in part by a transverse zone of the upper surface of thesleepers, intermediate of the rails and wherein the sleeper is formedwith a channel-shaped depression extending transversely across the uppersurface of the sleeper, said retention members being incorporated toeither side of the depression. According to an alternative embodiment,the retention means comprises an elongate member adapted to be fixed tothe sleeper to extend across the bed, each end of the elongate memberprovided with said retention members. According to a further embodimentthe retention means is fixed by at least one clip member which isclampingly engaged with the sleeper. According to one feature of theembodiment at least two clip members fix the retention means to thesleeper.

According to a further preferred feature of the invention, the flangesof the cover are inclined divergently with respect to each other.According to one embodiment the outer edge of each of the flanges isprovided with a laterally extending lip which in use is to be retainedbetween the retention members of the retention means and against theupper surface of the bed. According to a preferred feature of theinvention the lips are directed outwardly from the cover. According toan alternative feature of the invention the lips are directed inwardlyfrom the cover. According to a preferred feature of the invention thejunction of the flanges with the remainder of the cover is adapted toenable resilient flexing of the flanges as a result of said resilientdeformation.

According to a preferred feature of the invention the inner face of atleast one of the flanges of the cover is formed with an inwardlydirected extension which provides a support surface for the conductors.According to a preferred feature of the invention an extension isprovided on each of the flanges. According to a preferred feature of theinvention the extensions overlap, said extensions being resilientlydeformable to enable separation between the overlapping portions.According to an alternative form of the invention the inner face of thecover is provided with a partition which subdivides the space definedwithin the cover by the extensions into separate spaces. According toone embodiment the free edges of the extensions abut with the partitionand the extensions are capable of resilient deformation to separatetheir edges from the partition.

According to a preferred feature of the invention the bed is locatedbetween the rails.

According to a preferred feature of the invention the bed is locatedbeside one of the rails. According to one embodiment the bed is locatedbeside one of the rails and to the side of the rail remote from theother rail.

Accordingly the invention resides in an apparatus for enabling access tothe ducting associated with a rail track as described above, saidapparatus comprising an engaging means for causing resilient deformationof the cover to effect installation and/or withdrawal of the cover fromengagement with the bed, said engaging means comprising a pair ofopposed bearing members adapted to be engaged with opposed flanges ofthe cover, a drive means adapted to cause relative lateral movement ofthe bearing members with respect to each other and a motive meansadapted to cause longitudinal movement of the bearing members along thecover. According to a preferred feature of the invention, the bearingmembers each comprise a roller, the outer surface of which is configuredto engage the respective flange of the cover.

According to a preferred feature of the invention the engaging meanscomprises a clamping means. According to an alternative preferredfeature of the invention the engaging means comprises a separatingmeans.

According to a preferred feature of the invention the drive meanscomprises a plurality of axially spaced pairs of bearing members.

According to a further preferred feature of the invention, the apparatusis adapted to be supported from rails of the rail track to enablecontrolled movement of the means along the rail track. According to afurther preferred feature a lift means is associated with the drivemeans for effecting controlled upward and downward movement of one endof the drive means relative to the other end. According to a preferredfeature of the invention the apparatus further comprises an extractionmeans which is adapted to engage the conductor and extract or insert theconductors from or into duct on separation of the cover from the bed.

The invention will be more fully understood in the light of thefollowing description of several specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The description is made with reference to the accompanying drawings ofwhich:

FIG. 1 is a schematic cross-sectional elevation of a first embodiment ofthe invention;

FIG. 2 is a schematic cross-sectional elevation of a second embodimentof the invention;

FIG. 3 is a schematic cross-sectional elevation of a third embodiment ofthe invention;

FIG. 4 is an illustration of a branching arrangement which can beutilised with each of the embodiments of FIGS. 1, 2 and 3;

FIG. 5 is a schematic illustration of an apparatus which can be utilisedfor installation and withdrawal of the cover of each of the embodimentsof FIGS. 1, 2, 3 and 6 a to f;

FIG. 6 is an isometric view of a retention means and support accordingto a fourth embodiment of the invention;

FIG. 7 is a cross-sectional view of a retention means and supportaccording to a fifth embodiment of the invention;

FIG. 8 is an isometric view of a retention means and support accordingto a sixth embodiment of the invention;

FIG. 9 is a cross-section of a seventh embodiment of the invention;

FIG. 10 is a cross-section of an eighth embodiment of the invention;

FIG. 11 is a cross-section of a ninth embodiment of the invention;

FIG. 12 is a cross-section of a tenth embodiment of the invention;

FIG. 13 is a cross-section of a cover according to the eleventhembodiment of the invention;

FIGS. 14 a and 14 b is a cross-section of a cover according to thetwelfth embodiment and an insert which is receivable in the coverrespectively;

FIG. 15 is a side elevation of a retention means according to thethirteenth embodiment of the invention;

FIGS. 16 a to 16 f are cross-sectional views of alternative forms of theducting according to further embodiments of the invention;

FIGS. 17 a and 17 b are alternative forms of the cradle which can beused with the various embodiments in supporting the conductors.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Each of the embodiments of the invention are directed to means forproviding ducting association with a rail track whereby the ducting isable to accommodate conductors and the like without interruption ordisruption of the railway service associated with the rail track andwhich can be serviced with a minimum of disruption to the railwayservices associated with the rail track.

The first embodiment as illustrated at FIG. 1 comprises ducting which isassociated with a rail track comprising a pair of parallel rails 11supported on a set of regularly spaced sleepers 13. Each of the sleepersis formed with a central transversely extending recess 15 which definesa base 17 and outer edges 19 where each outer edge is formed with alaterally-extending groove 21. Each of the grooves 21 are lined with achip and abrasion-resistant material such as metal or the like. Therecesses 15 of sleepers of the rail track jointly define betweenthemselves a bed which is intended to accommodate conductors and thelike. The bed is further defined by a support 23 supported on the base17 of each recess 15 of each sleeper where the support is formed of anelectrical-insulating material which is also capable of providing atleast some vibrational insulation. The upper surface of the support isof an undulating configuration to provide a plurality oftransversely-directed grooves which are intended to receive andaccommodate the conductors and the like 25.

The bed which is associated with a cover 27 which comprises a pluralityof elongate lengths of channel which can be connected in end-to-endrelationship to provide a continuous cover over the bed defined by therecesses 15 of the sleepers 13 of the rail track. The flanges of thechannel are divergent with respect to each other and are provided attheir outer edge with an outwardly-directed lip 31. The cover hasdimensions such that in its relaxed state the lips 31 will be receivedin the lateral grooves 21 provided at the outer edges of each recess 15when the cover 25 is in position. The configuration of the junctionbetween each of the flanges 29 and the web 33 of the cover 25 isconfigured to provide a restraint against lateral forces which may begenerated parallel to the axis of the rollers of the apparatus used toapply and remove the cover which will be described in greater detailbelow. This is effected by forming the inner end of each of the flanges29 with a convergent portion 35 to provide a line of discontinuity alongthe width of the flange throughout which the remainder of the outerportion of the flange 29 can flex on application of an appropriatecompressive force to the opposed the flanges 29 of the cover.

In order to install the cover 27 in position over the bed, the flanges29 of the cover are inwardly compressed such that the spacing betweenthe outer edges of the lips 31 is less than the spacing between theouter edges 19 of the recess 15. This will then allow the cover to beintroduced into the recess 15 and on withdrawal of the compressionforces between flanges 29, the lips 31 will be capable of entering thelateral grooves 21 provided in the outer edges 19 of the recesses 15.

As a result of the embodiment, a duct is provided between the cover 25and the sleepers 13 of a rail track which is able to accommodate a setof conductors or the like. In the event that the cables accommodated bythe duct require servicing, the cover is readily removed to provide suchaccess to the conductors and the like. In addition, additional cablesand services can be introduced into the duct relatively easily withoutthe necessity to thread the additional cables into the duct.

The second embodiment as shown at FIG. 2 is generally of a similar formto that of the first embodiment and comprises a rail track comprising apair of parallel rails 111 supported upon a set of sleepers 113. Thesleepers are each formed with a central recessed portion 115. In thecase of the second embodiment the retention means comprises a pair ofopposed retention members 121 which are fixed to the sleeper at eitherside of the recess 115. The support of the second embodiment comprises atray 140 which extends along the length of the bed defined by therecesses 115 of the sleepers 113 of the rail track and which comprises aplurality of channel elements fixed in end to end relationship. The tray140 is supported from the base 117 of the recess 115 by a resilientmedium 142 which provides for some vibrational isolation between thesleeper 113 and the tray 140. The tray 140 comprises the support for theconductors or the like and is lined internally by a suitable medium 123which provides both electrical insulation and some vibrationalinsulation. The cover 127 is of a similar form to that of firstembodiment wherein the outer lips 131 are received in the retentionmembers 121 to positively retain the cover 127 in position. The internalface of the cover 127 is coated with a suitable thermal insulatingmaterial 137. The dimensions of the cover 127 are such that the thermalinsulating material will engage the upper edges of the tray 140 toisolate the space accommodating the conductors and the like 25 from theremainder of the space defined between the cover 127 and the recess 115.The outer edges of the insulating material 137 provided on the internalface of the cover 127 are formed as ribs 139 which will sealingly andsnugly engage the outer edges of the tray 140.

The third embodiment as illustrated at FIG. 3 comprises a rail tracksystem which comprises a pair of rails 211 supported upon a set ofpreformed slabs 213 which are located in end-to-end relationship alongthe length of the rail track. The upper surface of the slabs 213 areformed with a recess 215 of similar form to the recess of the firstembodiment which provides the bed. Lateral grooves 221 are provided ateach side of the recess 215 and are intended to receive the lips 231 ofa cover 227 of a similar form to that described in relation to the firstembodiment. The recess 215 accommodates a support tray 240 of similarform to that of the second embodiment which accommodates the conductors225 and the like in a similar manner and which cooperates with the cover227 in a similar manner.

FIG. 4 is an illustration of a branching arrangement which can beutilised with each of the embodiments described above. The purpose ofthe branching arrangement is to allow for the interconnection of thecables, conductors and the like with external users. The branchingarrangement comprises a tunnel 51 which is provided underneath the railtrack through which branching cables 52, 53 and pass to and from theduct provided in the rail track. In addition, FIG. 4 schematicallyillustrates the location of ancillary hardware 55 which is required foroperation of the rail track. In this regard the hardware 55 can besupported upon support plates 57 which bridge the cover 27 wherebycables, pipes or the like 59 which are associated with the hardware 55can pass laterally from the rail track.

FIG. 5 schematically illustrates apparatus which can be utilised forinstallation and retraction of the cover 27, 127 and 227 of each of theembodiments described above. Whilst the apparatus will be described inrelation to installation removal of the cover plate 27 of the firstembodiment, it has equal application to each of the other embodiments.

The apparatus comprises the clamping means for engaging the opposedflanges 29 of the cover 27 to cause inward resilient deformation of theflanges 29 to enable the lips 31 to be disengaged from the lateralgrooves 21 of the recesses and subsequently raise the cover 27 fromengagement with the recesses. The clamping means comprises a set ofpairs of rollers 71 where the pairs of rollers are longitudinally spacedfrom each other. The rollers 71 of each pair are transversely spacedsuch that they are capable of being located to either side of the cover27 to engage the opposed flanges 29 outward of the line of discontinuityprovided in the flanges. A compression means (not shown) is providedbetween each pair of rollers whereby with movement of the rollers ofeach pair towards each other under the influence of the compressionmeans, the flanges 29 are resiliently compressed. The clamping means issupported from a carriage 73 which is in turn supported from the railsof the rail track to be capable of movement along the rail track. Inaddition a lifting means is provided between one end of the clampingmeans and the carriage 73 to enable the one end to be raised and loweredrelative to the other end.

The arrangement is such that the set of rollers will engage the coverplate and cause compression of the flanges 29 of the cover plate. Oncethe flanges 29 having been compressed the length of cover plate can thenbe raised out of position from the bed to be removed to permit servicingof the duct.

It will be appreciated that the installation of the cover over the bedwill comprise a reverse process to the removal action described above.

According to a second embodiment of the apparatus of embodiment thecontraction of the rollers of the clamping means is graduated along thelength of the clamping means such that the cover when initially engagedby the rollers at the other end of the clamping means is partiallycompressed and the degree of compression increased until at the one endof the clamping means the cover has been fully compressed such that thelips 31 can be removed from the retention means. In addition thecarriage 73 is driven to be movable along the track whereby the otherend of the clamping means is the leading end. As a result the apparatuscan be used to continuously move along the rail track to remove thecover from the bed whereby each length of channel once removed from thebed can be positioned clear of the track.

According to a further embodiment the apparatus for servicing the covermay comprise a single set of apparatus which is able to remove the coverfrom the bed and subsequently replace the cover in position over thebed. The apparatus comprises a duplication of the previous embodiment toprovide a pair of clamping apparatus supported from a single carriagewhere the other end of the pair of clamping apparatus are in opposedrelationship. As a result the apparatus can be used to lift the coverfrom the bed in a continuous action as the carriage is caused to movealong the rail track and which will expose the bed to enable theservicing of the ducting (eg by introduction of a fresh conductor andthe like or replacement or removal of an existing conductor and thelike) and the subsequent reinstallation of the cover in position overthe bed.

The fourth, fifth and sixth embodiments of the invention as shown atFIGS. 6, 7 and 8 each comprise an arrangement which is a variation ofthe second embodiment where the retention means 320 comprises a singlemember which incorporates each of the retention members 321 which arelocated in opposed relation to each other at each end of a central stripshaped web element. In each case the retention means is fixed to thesleeper 313 by a pair of clip members 322 which are in each caseconfigured to straddle the sleeper and are formed with a pair ofresilient legs 324 which are configured such that they must beresiliently deformed to be received over the sleeper.

In the case of the fourth and fifth embodiment of the invention a shownat FIGS. 6 and 7 where the central portion of each clip member isconfigured to engage the upper face of the central strip shaped webelement of the retention member 320 and hold it in place. In the case ofthe sixth embodiment the central strip shaped web element of theretention member 320 is bolted to the clip members.

In the case of the fourth and fifth embodiments as shown at FIGS. 6 and7 the clamping engagement between the clip members 322 and the retentionmeans 320 is enhanced by use of a resilient compressible sheet element326 which is located between the retention member 320 and the sleeper313 and which is compressed by the application of the clip members tothe sleeper.

In the case of the sixth embodiment the underneath of the clip member322 is lined by a layer 328 of a resiliently compressible material suchas a suitable elastomer or like material.

In each of the fourth fifth and sixth embodiments the retention meanssupports a support 340 in the form of a cradle formed of a suitablematerial which provides for electrical and some vibrational insulationto the cables which extend along the track over the spaced cradleslocated above each of the sleepers of the track.

The use of the fourth, fifth and sixth embodiments of the invention asshown at FIGS. 6, 7 and 8 facilitates the application of ductingaccording to the invention to an existing railway track. In addition theuse of the resilient clip members enables the ducting to accommodate formovements of the track with out significantly imposing any adverseforces upon the track

FIG. 9 illustrates a the seventh embodiment of the invention where thelower edge of each flange 429 of the cover 427 is formed with aninwardly directed extension 451. The extensions overlap at theirinnermost extent and the extension which lies innermost is formed withan upwardly directed lip 453. The inner surface of each of theextensions provide a support surface for the conductors 425 the cover ofthe embodiment is formed from sheet metal and the extensions comprisefolded formations at the edges of the flanges which form both the lips431 as well as the extensions. In addition the material of which thecover is formed permits some resilient deformation of the cover tofacilitate its engagement with the recesses of the retention means andresilient deformation of the extensions to enable conductors 425 to beintroduced into the duct defined by the cover or removed from the ductby separation of the overlapping edges of the extensions. In additionconnectors 455 are used to interconnect the abutting ends of adjacentlengths of cover. The connectors 425 have a an external profile which iscomplementary to at least a portion of the inner profile of the cover toenable them to be snugly received within the cover and have a lengthsuch that they extend for a short distance along the adjacent lengths ofcover.

The eighth embodiment as shown at FIG. 10 is of a generally similar formto that of the seventh embodiment with the exception that the cover isformed of a suitable plastics or elastomeric material and has a geometryto accommodate for the material of which it is formed. As a result thesame reference numerals which are used in FIG. 9 are used in FIG. 10 forcorresponding elements.

The ninth embodiment as shown at FIG. 11 is of a generally similar formto that of the eighth embodiment and has a cover which is also formed ofa suitable plastics or elastomeric material and has a geometry toaccommodate for the material of which it is formed. As a result the samereference numerals which are used in. FIGS. 9 and 10 are used in FIG. 11for corresponding elements. In the case of the ninth embodiment theextensions 451 do not overlap but are associated with a partition 457which is formed to extend across the interior of the cover to terminatewith an enlarged rib 459 which is located between the opposed edges ofthe extensions 451 to define separate ducts within the cover which canbe accessed with resilient deformation of the extensions 451.

The tenth embodiment of the invention as shown at FIG. 12 utilises acover which is also formed of a suitable plastics or elastomericmaterial and has a geometry to accommodate for the material of which itis formed. In the case of the tenth embodiment the inner face of web ofthe cover 527 between the flanges 529 is formed with a set of ducts 561which are located in side by side relationship across the web and whichare each intended to accommodate a conductor 525. Each duct is formedwith a slit 563 which extends for the length of the cover and whichprovides the entry to the duct to enable a conductor to be inserted intothe duct or extracted from the duct.

The eleventh embodiment of the invention as shown at FIG. 13 utilises acover 627 having the configuration of a channel in which the flanges 629are divergent but are not provided with lips at their edges 665 as hasbeen the case with previous embodiments and which is also formed of asuitable resilient material. In use the edges 665 of the flanges arereceived between opposed lips 667 provided on the retention means 620.

The twelfth embodiment of the invention as shown at FIGS. 14 and 14 b isof a similar form to that of the tenth embodiment as shown at FIG. 12with the exception that it is formed as a 2-part element comprising acover 727 as shown at FIG. 14 a which is of a generally similar form tothe cover of the first embodiment and is formed of a suitable sheetmetal and which is associated with an insert 771 which is formed of asuitable plastics or elastomeric material which is snugly receivablewithin the cover and which provides a plurality of ducts 761 foraccommodating conductors which can be inserted into the ducts throughslits 763

FIG. 15 illustrates a retention means 820 according to the thirteenthembodiment of the invention. The retention means of the thirteenthembodiment is a variation of the fourth, fifth and sixth embodiments ofthe invention as shown at FIGS. 6, 7 and 8. In the case of thethirteenth embodiment the compressible sheet material is no longerpresent. Instead the retention means is supported at each end by a rib873 provided on the under surface of the retention means which is inturn supported from the bed 813 and as a result the central portion ofthe retention means is spaced above the bed 813. The retention means isfixed at its central portion to the bed by a suitable fixing 875 whichserves to place the retention means in a state of tension on the fixingmeans being tightened. In addition the ribs 873 are supported from thebed 813 through a resiliently compressible material 877 which is locatedbetween the rib and the bed prior to application of the fixing means.

FIGS. 16 a to f illustrate various alternative embodiments of theinvention illustrating various relationships between the cover 927,retention means 920 and support 923 for the conductors or the like inwhich the reference lines A and B illustrate the position of the flangeswhen engaged with the retention means 920 and when compressedrespectively.

FIGS. 17 a and 17 b illustrate two forms of support 1023 which can beused with each of the embodiments and which provide a number oflaterally spaced recesses 1079 which can each be used to accommodate aplurality of conductors (not shown). Each recess 1079 is formed with aset opposed ribs 1081 which each define a space 1083 for accommodating asingle conductor which is of an oval or ellipsoidal configuration wherethe spacing between the outer edges of the ribs 1081 corresponds to theminor dimension of the conductor and the spacing between the base ofeach space corresponds substantially with the major dimension of theconductor.

Each of the embodiments provide a means for providing ducting inassociation with a rail track whereby the ducting is capable of beinginstalled and regularly serviced for the introduction of additionalcables or repair to existing cable without adverse influence to therailway service being associated with the rail track. In addition eachof the embodiments provide a ducting in which the increasing demands foradditional conductors and the like can be accommodated without unduedisruption to existing infrastructure.

Throughout the specification, unless the context requires otherwise, theword “comprise” or variations such as “comprises” or “comprising”, willbe understood to imply the inclusion of a stated integer or group ofintegers but not the exclusion of any other integer or group ofintegers.

It should be appreciated that the scope of the present invention neednot be limited to the particular scope of the embodiments describedabove.

1. Ducting on a railroad rail track, comprising a pair of parallel railssupported from a base, the base providing a bed proximate the rails andco-extensive with the rail track, a cover receivable over the bedcomprising a plurality of elongate channel members located in end to endrelationship having their flanges extending downwardly, said cover beingmounted on the bed and defining a duct accommodating at least one of aconductor, cable and conduit, retention means mounted on the bed andadapted to receive and retain the edges of the channel members, saidedges being selectively engagable and/or disengageable with theretention means by application of opposed and inwardly directed forcesto the edges to cause resilient inward displacement of the edges fromthe retention means.
 2. Ducting as claimed at claim 1 wherein adjacentlengths of said channel members are interconnected by sleeves whichextend between the abutting ends of adjacent channel members.
 3. Ductingas claimed at claims 2 wherein the edges of the channel members are atleast partially retained by the retention means by a resilientdeformation induced by engagement with the retention means.
 4. Ductingas claimed at claims 1 wherein the dusting further comprises a supportfor said at least one of a conductor, cable and conduit which extendsalong the length of the bed.
 5. Ducting as claimed at claim 4 whereinthe support provides electrical insulation.
 6. Ducting as claimed atclaim 5 wherein the support provides at least some vibrationalinsulation.
 7. Ducting as claimed at claim 6 wherein the support issupported from the bed.
 8. Ducting as claimed at claim 7 wherein thesupport comprises a plurality of cradles located at spaced intervalsalong the bed, said cradles having a recessed upper surface which isadapted to accommodate said at least one of a conductor, cable andconduit.
 9. Ducting as claimed at claim 8 wherein the rail trackincorporates sleepers which support the rails and which are located atregular spaced intervals along the length of track, said bed beingdefined in part by a transverse zone of the upper surface of thesleepers and wherein the transverse zone accommodates the support. 10.Ducting as claimed at claim 9 wherein the transverse zone of thesleepers is recessed.
 11. Ducting as claimed at claim 7 wherein, thesupport comprises a tray extending along the bed and defined by aplurality of interconnected elongate, upwardly directed channel memberssupported in end-to-end relationship.
 12. Ducting as claimed at claim 11wherein the flanges provided on the tray comprise the retention means.13. Ducting as claimed at claim 12 wherein the flanges provided by thetray are inclined to be convergent towards each other, said flangesbeing adapted to receive between themselves the edges of the cover. 14.Ducting as claimed at claim 11 wherein the base of each of the trayaccommodates an elongate support element adapted to receive theconductors and the like.
 15. Ducting as claimed at claim 11 wherein, atleast some of the conductors or the like are embedded within thesupport.
 16. Ducting as claimed at claim 14 wherein, the surface of thesupport element is of a recessed cross-sectional profile.
 17. Ducting asclaimed at claim 16 wherein the recesses provided in the support elementare adapted to support the conductors in a one to one relationship. 18.Ducting as claimed at claim 17 wherein the recesses are spacedvertically with respect to each other.
 19. Ducting as claimed at claim 4wherein the support is associated with a closure which is intended to bereceived over the support to isolate the conductors or the like from theremainder of the duct.
 20. Ducting as claimed at claim 19 wherein, thecover is adapted to cooperate with the support to enclose the conductorsand the like accommodated by the support.
 21. Ducting as claimed atclaim 4 wherein the support is supported from the cover and is formedwith at least one recess which is adapted to support the conductor. 22.Ducting as claimed at claim 21 wherein the support and cover areintegral and the recess is formed on the inner face of the cover. 23.Ducting as claimed at claim 21 wherein the recess is substantiallyclosed and is provided with an entry which is normally closed and can beopened on deformation of the support.
 24. Ducting as claimed at claim 1wherein the retention means comprises a pair of retention memberssupported from the bed at spaced intervals there along, the retentionmembers of each pair being spaced to either side of the bed, the edgesof the cover being received between the retention members.
 25. Ductingas claimed at claim 8 wherein the rail track incorporates sleepers whichsupport the rails and which are located at regular spaced intervalsalong the length of track, said bed being defined in part by atransverse zone of the upper surface of the sleepers and wherein thesleeper is formed with a channel-shaped depression extendingtransversely across the upper surface of the sleeper, said retentionmembers being incorporated to either side of the depression.
 26. Ductingas claimed claim 24 wherein, the retention means comprises an elongatemember adapted to be fixed to the bed to extend across the bed, each endof the elongate member provided with said retention members.
 27. Ductingas claimed at claim 26 wherein the retention means is fixed by at leastone clip member which is clampingly engaged with the sleeper. 28.Ducting as claimed at claim 27 wherein at least two clip members fix theretention means to the sleeper.
 29. Ducting as claimed at claim 1wherein the flanges of the cover are inclined divergently with respectto each other.
 30. Ducting as claimed at claim 1 wherein the outer edgeof each of the flanges of the cover is provided with a laterallyextending lip which in use is to be retained between the retentionmembers of the retention means and against the upper surface of the bed.31. Ducting as claimed at claim 30 wherein the lips are directedoutwardly from the cover.
 32. Ducting as claimed at claim 28 wherein thelips are directed inwardly from the cover.
 33. Ducting as claimed atclaim 1 wherein the junction of the flanges of the cover with theremainder of the cover is adapted to enable resilient flexing of theflanges as a result of said resilient deformation.
 34. Ducting asclaimed at claim 1 wherein at least one of the flanges of the cover isformed with an inwardly directed extension which provides a supportsurface for the conductors.
 35. Ducting as claimed at claim 34 whereinthe extension is provided on each of the flanges.
 36. Ducting as claimedat claim 35 wherein the extensions overlap, said extensions beingresiliently deformable to enable separation between the overlappingportions.
 37. Ducting as claimed at claim 35 wherein the inner face ofthe cover is provided with a partition which subdivides the spacedefined within the cover by the extensions into separate spaces. 38.Ducting as claimed at claim 37 wherein the free edges of the extensionsabut with the partition and the extensions are capable of resilientdeformation to separate their edges from the partition.
 39. Ducting asclaimed at claim 1 wherein the bed is located between the rails. 40.Ducting as claimed at claim 39 wherein the bed is located beside one ofthe rails.
 41. Ducting as claimed at claim 1 wherein the bed is locatedbeside one of the rails and to the side of the rail remote from theother rail.
 42. Ducting as claimed at claim 11 wherein the support isassociated with a closure which is intended to be received over thesupport to isolate said at least one of a conductor, cable and conduitfrom the remainder of the duct.
 43. Ducting as claimed at claim 42wherein, the cover is adapted to cooperate with the support to enclosesaid at least one of a conductor, cable and conduit accommodated by thesupport.
 44. Ducting as claimed at claim 42 wherein at least one of theflanges of the cover is formed with an inwardly directed extension whichprovides a support surface for said at least one of a conductor, cableand conduit.
 45. Ducting as claimed at claim 44 wherein the extension isprovided on each of the flanges.
 46. Ducting as claimed at claim 45wherein the extensions overlap, said extensions being resilientlydeformable to enable separation between the overlapping portions. 47.Ducting as claimed at claim 45 wherein the inner face of the cover isprovided with a partition which subdivides the space defined within thecover by the extensions into separate spaces.
 48. Ducting as claimed atclaim 47 wherein the free edges of the extensions abut with thepartition and the extensions are capable of resilient deformation toseparate their edges from the partition.
 49. Ducting as claimed at claim43 wherein at least one of the flanges of the cover is formed with aninwardly directed extension which provides a support surface for said atleast one of a conductor, cable and conduit.
 50. Ducting as claimed atclaim 49 wherein the extension is provided on each of the flanges. 51.Ducting as claimed at claim 50 wherein the extensions overlap, saidextensions being resiliently deformable to enable separation between theoverlapping portions.
 52. Ducting as claimed at claim 50 wherein theinner face of the cover is provided with a partition which subdividesthe space defined within the cover by the extensions into separatespaces.
 53. Ducting as claimed at claim 52 wherein the free edges of theextensions abut with the partition and the extensions are capable ofresilient deformation to separate their edges from the partition. 54.Ducting as claimed in claim 1, wherein said duct is capable ofaccommodating at least one of a conductor, cable and conduit.